A number of small molecules which act as tyrosine kinase inhibitors have been identified. For example, certain compounds have been described as tyrosine kinase inhibitors, effective to inhibit cell proliferation (see for example, U.S. Pat. Nos. 5,891,917, 5,217,999, 5,773,476, 5,935,993, 5,656,655,  5,677,329, 5,789,427 and WO 01/79158). However, there remains a need for compounds that selectively target one or more such kinases, e.g., to preferentially inhibit proliferation of cancerous cells over normal cell proliferation.